Too many toolbar redraws

Jeff Sparkes writes:

 > It appears that the toolbar is being cleared and recreated for every
 > redraw.

Great!  I've been looking forward to a patch addressing unnecessary
redrawing for a long time!

It'll be a day or so before I can review, and I can't really address
Windows issues (see below for why that might matter).

 > I have a patch that only clears the toolbars if the frame is
 > resized, which seems to be the original intent.  I'm not sure if
 > the toolbar even needs to be cleared on the resize, but this patch
 > saves a lot of churn.

Since toolbars can be placed on the right side and bottom, and even
top and left can have a button (typically Help) at the far end, it's
certainly true that some parts of all toolbars, and all of some
toolbars, *need* to be redrawn on resize.

Note to Windows users:

I suspect this was Windows-related, or at least done by a Windows
coder.  There are many places where subwindows are dirtied explicitly,
which is way inefficient in Xt or GTK+ coding.  At least from the
XEmacs code I've looked at, it doesn't seem like Windows has a proper
notion of "widget", so you need to redraw stuff "by hand" all the
time.